Choline group

Figure 13. The overall density (volume fraction) profile for DMPC bilayers is shown here. Apart from the distribution of the overall DMPC molecules, the density distribution of the head-group units (including the choline group, the phosphate group and the oxygens of the glycerol unit), and the end groups of the lipid tails are also indicated. In addition, the free-volume profile and the water profile are depicted...

Figure 14. Volume-fraction profiles of parts of the DMPC molecules for lipids that have the head group at positive coordinates (continuous lines) and at negative coordinates (dashed lines). The centre of the bilayer is positioned at z — 0. The phosphate group, the nitrogen of the choline group and the CH3 groups of the tail ends, as well as the other hydrocarbon units, are indicated...

One would expect that deprotonated substituted phenols interact with the positively charged choline group [172]. However, 31P-NMR studies on the... 

This lamellar phase is formed of alternate sheets of lipid and water. The lipidic sheets containing the lecithin and the cholesterol are made of two superposed layers of oriented molecules. Each of these two monolayers is mixed and consists of lecithin and cholesterol molecules arranged side by side with their paraffinic ends turned toward the inside of the sheet and their polar groups (phosphatidyl choline group for lecithin and hydroxyl group for the cholesterol) outward—i.e., toward the adjacent sheet of water. This constitution of each of the two mono-layers forming the lipidic sheet is in conformity with the conclusion arising from the study of mixed monolayers of cholesterol and lecithin spread on the free surface of water (1). 

La water-lecithin is a lamellar structure in which the polar heads (the phosphatidyl choline group of lecithin) constitute two-dimensional disordered arrays in contact with water, whereas the chains are in the molten state in between water layers in disordered moieties (see Figure 1). (For a review of x-ray studies of lecithin-water phases, see Ref. 11.)... 

As shown in Figure 10 the water deuteron quadrupole splitting increases with increasing electrolyte concentration. This may well fit with the model discussed above if the postulated conformation change of the polar head groups consists of a stretching out of the choline groups away... 

The presence of a choline group led to the possibility of attaching (3-galactosidase from Escherichia coli connected to choline-binding domain of (acetylmuramoyl)-L-alanine amidase from Streptococcus pneumoniae. With respect to the... 

The three-dimensional structure of AChE from the electric organ of Torpedo californica has been established. One interesting feature is that the active site is embedded in a gorge of 20 A that reaches halfway into the protein. The postulated anionic site , theoretically invoked to bind the quaternary ammonium ion of ACh, appears to be represented by aromatic amino acids in the gorge itself these and charges in the active center are believed to stabilize the choline group. In addition, some inhibitions, such as that due... 

CH2) and 1735 cm (C=0). Additional Raman bands are assigned to the choline groups of hydrophilic lipid head groups (717 cm ) and to C=C groups in unsaturated fatty acid side chains (1267, 1657cm ). There are numerous bands of the aromatic system of cholesterol with the most intensive IR bands at 1053, 1364, 1376 and 1466cm (trace F) and the most intensive Raman bands at 427,... 

In regions rich in PC, the hydrophobicity of the choline group will pull it towards the membrane phase. This orientation would make the phosphate group, and hence its charge, exposed to the water phase. This region has 18 to 20 water molecules per lipid, and OH groups from solutes such as phloretin have access both to phosphates and carbonyls. 

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